1. Field of the Invention
Embodiments disclosed here generally relate to a downhole debris retrieval tool for removing debris from a wellbore. Further, embodiments disclosed herein relate to a downhole tool that includes magnets for removing debris from a wellbore.
2. Background Art
A wellbore may be drilled in the earth for various purposes. For example, wellbores may be drilled to extract hydrocarbons, geothermal energy, or water. After a wellbore is drilled, the wellbore is typically lined with casing to preserve the shape of the wellbore and to provide a sealed conduit for fluid transportation.
It is beneficial to keep a wellbore clean because many complications may occur when debris collects therein. For example, accumulation of debris may prevent free movement of tools through the wellbore during operations, interfere with production of hydrocarbons, and/or damage tools. Different types of debris may include cuttings produced from the drilling of a wellbore, metallic debris from various tools and components used in drilling operations, and debris from the corrosion of the wellbore casing. Smaller, lighter debris may be circulated out of the wellbore using drilling fluid; however, drilling fluid may not be capable of returning larger, heavier debris to the surface. In particular, horizontal wells and significantly angled portions of deviated wells may be more likely to collect debris. Because this problem is well known in the art, many tools and methods have been developed to help maintain clean wellbores.
One type of well-known tool for collecting debris is the junk catcher, sometimes referred to as a junk basket, junk boot, or boot basket, depending on the particular configuration and the particular debris to be collected. Although many junk catchers known in the art rely on various mechanisms to capture debris, most use the movement of fluid in the wellbore to transport debris to a desired location. Fluid may be moved within the wellbore by surface pumps or by movement of the string of pipe to which the junk catcher is connected. Hereinafter, the term “work string” will be used to collectively refer to the string of pipe or tubing in addition to all other tools that may be used with the junk catcher. For describing fluid flow, the term “uphole” refers to a direction toward the surface, relative to a location inside the wellbore. Additionally, the term “downhole” refers to a direction extending into the formation from a surface opening of a wellbore, relative to a location inside the wellbore.
Some junk catchers known in the art use a combination of flow diverters and screens to separate debris from drilling fluid, as shown in FIGS. 1A and 1B. Such junk catchers 10 may deposit large or heavy debris into a storage container 12 using a mechanism such as a flow diverter 14. Debris that remains suspended in the drilling fluid may then pass into a second stage of filtration. In some configurations, the second stage may include a chamber fitted with a screen 16 through which drilling fluid flows. Debris suspended in the drilling fluid that is of an allowable size will pass through the screen 16 while debris that is too large will not. In some configurations, debris may become stuck in the screen 16, thus clogging the tool and preventing internal fluid flow and suction.
Accordingly, there exists a need for a junk catcher tool capable of effectively removing debris from a wellbore. Specifically, there exists a need for a junk catcher with a mechanism for preventing clogging of a screen.